1. Field of the Invention
The present invention relates to an apparatus which is associated with an image forming apparatus, such as an electrophotographic copying apparatus, for sorting sheets of paper discharged from the image forming apparatus.
2. Description of the Related Art
In recent years, image forming apparatuses are widely used, and a variety of image forming apparatuses having a sorter are now in practical use.
A sorter of this kind is generally provided with a paper receiving unit which comprises a plurality of paper receiving trays vertically piled up. The entire receiving unit is vertically moved to successively place a desired receiving tray in front of the discharge rollers of the image forming apparatus, thereby receiving printed sheets of paper discharged from the apparatus and storing them.
Since, however, the whole paper receiving unit having such a structure must be moved along with the stored paper sheets, these sorters are complicated and large. In addition, the sorter requires a large driving force and power, resulting in increase in manufacturing cost.
A sorter disclosed in a Published Examined Japanese Patent Application No. 2-29577, for instance, includes a paper receiving unit having a plurality of paper receiving trays, a movable guide for guiding the paper sheets discharged from the image forming apparatus to their respective paper receiving trays, and feed rollers arranged on the end of the guide in such a manner that the rollers vertically move in a direction in which the paper receiving trays are piled up, in interlock with the movement of the guide, for feeding the guided paper sheets into their respective paper receiving trays. A sorter with this structure can surely solve the above problem.
However, in the above-mentioned sorter, a space is defined between the paper receiving unit and the feed rollers so as to prevent the movement of the discharge rollers from being obstructed by the receiving unit. This space may hamper the sure feeding of a paper sheet from the feed rollers to the paper receiving tray. Specifically if a space exist between the feed rollers and the receiving tray, a paper sheet is not fed completely into the receiving tray and the rear end of the paper sheet projects from the tray into the space. The projected portion of the sheet may hinder the sorting and storing operations for the following paper sheets, resulting in a paper jam.